East Veil in H-a and O-III
The East Veil Nebula, NGC 6992/6995 and IC 1340, taken through narrowband filters (hydrogen is red, oxygen blue).
Part of an almost-circular supernova remnant in Cygnus. The whole Cygnus Loop is about 3 degrees wide (6X the full Moon's diameter); this view is about 1 degree or so.
It's about 1400-1500 light years away, the supernova exploded something like 8000 years ago.
Taken in the absurdly light-polluted setting of the Demtral Dog Park using hydrogen-alpha and oxygen-III 7-nm filters. 60-second exposures, unguided. Stellarvue SV70t-IS, ASI183MM Pro camera.